1. Field of the Invention
The present invention relates generally to the field of wireless communication devices. More particularly, the present invention relates to a wireless communication device for compatible operation with hearing aid devices.
2. Introduction
Wireless communication devices or mobile phones are often not compatible with many hearing aids due to the potential for radio frequency (RF) interference in the form of scattered electro magnetic fields generated by the devices while in use. When a mobile phone is in communication with its network, an electromagnetic field (e-field) is present around the mobile phone antenna. The pulsing energy of the e-field is picked up by the hearing aid's microphone or telecoil circuitry and heard as a buzzing sound through the hearing aid.
The Federal Communication Commission has mandated that phone manufacturer's models be Hearing Aid Compatible (HAC). HAC compliance constrains E and H fields in a measurement plane above the earpiece (speaker) to be below a specified level. Because of the power levels involved and the details of how the digital modulation produces audible interference, this requirement is particularly onerous for Global System and for Mobile Communications (GSM) phones, which are often challenged to meet the required field values while maintaining good call performance.
Therefore, a HAC-reduction technique is needed for various phone form factors and designs, to ensure compliance with this mandate. In particular, clam and slider phones comprise a large fraction of phones sold in the US market, and require HAC solutions that will not degrade the other radiated performance parameters.